CHAPTER VIII

FORM--_Continued_. TOOLS AND IMPLEMENTS SHAPED FOR EFFICIENCY

Edge tools old and new . . . Cutting a ring is easier than cutting away a whole circle . . . Lathes, planers, shapers, and milling machines far outspeed the hand . . . Abrasive wheels and presses supersede old appliances . . . Use creates beauty . . . Convenience in use . . . Ingenuity may be spurred by poverty in resources.

Tools and Implements.

We have just reviewed, all too briefly, how light and heat are economized by structures of judicious form. At this point we will bestow a rapid glance at the economy of work as promoted by sound design in tools and implements, in the machines which embody these for tasks far beyond the personal skill or power of the strongest and deftest mechanic.

When of old a savage took up a stone to serve as a rude knife or chisel, we may be sure that he chose the sharpest flint he could find. If he could better its shape by knocking it into something like a wedge, what task was easier? Our museums display an immense variety of stone hammers, axes, knives, and arrowheads, showing how art long ago improved the forms of simple tools and weapons offered by nature. Modern tools and weapons, for all their immense diversity, were every one prefigured in the rude armory of primitive man.

Descended from his flint knife is the abounding variety of steel cutting tools all the way from the razor, concave on both sides, to the axe, doubly convex. As the arts have become more specialized, as artificial power has been introduced, the contrasts of the form of one tool with another have grown more and more striking. The bar which slices metal is stout of build, and rectangular in section, while a lancet is little wider or thicker than a blade of grass. The knives which divide leather, rubber, and rope, differ much from one another; the knife which separates the leaves of a book serves best when dull. Gouges for carving are nicely adapted to the profiles they are to cut; while the exigencies of the power-lathe require its tools to be designed of particular strength and rigidity. Among revolving hand-tools the brace is the most important, enabling the workman to exert great leverage. A minor tool, the gimlet, was formerly more in use than to-day. Now that screws are made with gimlet points they break their own paths.

From the beginning tool-makers have shown skill in fitting a tool to the hand, as in the Eskimo skin-scraper; this simple adaptation may have arrived in copying the effect of wear. Other good hints have come from observing an implement after its work is done. At the places where mud clung to a plowshare the plow-maker was long ago told at what points to raise his metal; conversely, when a cutter of any kind is unduly worn at any part of its side, there the metal asks to be somewhat narrowed down.

Annular Drills.

A circle of say two feet in diameter, may be readily cut from a boiler plate by two cutters, one at each end of a horizontal bar, the bar being supported by a central upright axis receiving the motive power. Because the cut is narrow, but little metal is wasted as chips. A cut of this ring-shape effects a desirable saving even when the circle to be swept is but an inch or so in width instead of several feet. When an auger takes its way through a plank it removes as chips all the wood within the circle of its range; a drill, of common form, as it pierces stone or metal acts in a similar manner. Motive power is greatly economized when a drill is tubular, with the further advantage that within the ring cut a solid cylinder remains to be broken off at intervals and lifted out, its core informing to the engineer in quest of bed-rock, to the prospector of mines or oil-fields, or to the geologist who reads at a glance the composition of a mineral, the forces which have impressed it age after age. Such drills, set with bortz diamonds, have accomplished remarkable feats. In boring out 260 columns surrounding the dome of the capitol at Springfield, Illinois, cores 22-3/4 inches in diameter were removed from holes 24 inches wide; without sacrifice of strength there was a saving in weight of three-fifths. At the Ellenwood coal mine, Kingston, Pennsylvania, a core 17 feet, 5 inches in breadth was taken from a bore only five inches wider. When the engineers in 1896 were planning the foundations for the Williamsburg Bridge, New York, the deepest of their 22 borings was 112 feet below high water. Steel drills had indicated bed-rock 12 to 20 feet higher than was the actual case; the diamond drill showed the supposed bed-rock to be merely a deposit of boulders. No other known means could have accomplished these results. In the same way steel guns of large calibre have been drilled so as to leave a core of much value, while in this as in all other such tasks, the boring demanded less energy and proved less straining than if all the metal within the sweep of the drill had been reduced to fragments. All these tools were prefigured in a simple ring drill used two thousand years ago on the banks of the Nile; hollow reeds were employed, with sand as a cutter.

Twist Drills.

Twist drills are superseding flat drills as stronger and better in every way. A twist drill is made with a slight taper toward the shank end. Its cross-section is not quite round, the diameter being reduced from a short distance behind the cutting edge, so as to diminish friction and give the sides of the drill as much clearance as possible. The advanced edges of the flutes are all full circle, so as to maintain the diameter of the drill and keep the tool steady. The advantage of the twist drill is that its cuttings find free egress, while it always runs true, without reforging or retempering. The cutting edges are usually ground to an angle of sixty degrees to the center line of the drill; for brass work the angle should be fifty degrees.

Lathe and Planer Tools.

The manner in which a lathe tool cuts metal is shown in an outline which represents a tool feeding a cut along a piece of wrought iron. The removed metal, in its diameter and openness, tells the expert operator both the quality of his cutter and how it is being affected by wear. The principal consideration, says Mr. Joshua Rose, in determining the proper shape of a cutting tool, for use in a lathe or a planer, is where it shall have the rake, or inclination, to make it keen enough to cut well, and yet be as strong as possible; this is governed, in a large degree, by the nature of the work.

Machine Tools: Lathes.

In giving form to wood and metal cheaply and rapidly, machine-tools have within recent years risen to great importance. Of these the lathe is one of the chief. It seems to be descended from the bow drill, the tool which was whirled by a cord wrapped round it, or it may be, that under another sky, the lathe was derived from the potter’s wheel whose axle was changed from a vertical to a horizontal plane. For centuries all lathes had their cutting tools simply laid on a bar, or rest, just as in the hand cutting lathe of to-day. While this afforded opportunity to skill it did not lend itself to large or uniform production. Henry Maudslay, about a century ago, immensely broadened the machine in scope by devising the slide rest which firmly grasps the cutting tool, and automatically moves it toward or away from the axis of the work, as well as along the work in any desired line. This device is equally applicable whether in turning a pencil case, the granite columns for a cathedral, or the propeller-shaft of an ocean steamer.

The lathe has been developed in many ways until it has become one of the most complex of all machines, adapted to tasks which even twenty years ago seemed impossible. Only two of its varieties can here be noticed, the Blanchard lathe for cutting irregular forms, and the turret lathe. An illustration, taken from an old engraving shows the Blanchard lathe as originally built for shoe-lasts. A pattern-last and the block to be carved are fixed on the same axis and are revolved by a pulley. On a sliding carriage are fastened pivots from which are freely suspended the axles of a cutting wheel, and a friction wheel, equal in diameter. The cutting wheel turns on a horizontal axle, and bears on its periphery a series of cutters. The friction wheel is in contact with the pattern-last and presses against it while in motion. During revolution, the pattern, irregular in its surface, causes the axis to approach or recede from this friction wheel; the cutting wheel in its corresponding motion removes wood from the block until a duplicate of the pattern appears. This lathe much improved and modified now turns not only gun-stocks, axe-handles and the like, but repeats elaborate carvings with precision. Ornaments for Pullman cars are produced by this machine.

The turret lathe, equally ingenious, has a turret or capstan, which carries let us say eight different tools, one on each of its eight faces. In its turn each tool operates on the work in its forward traverse; it then retires while the turret automatically moves through one-eighth of a circle, when the next tool emerges for its task, and so on.[7]

[7] The turret principle is embodied in drills and a variety of other machines. It was adopted in remarkable fashion by John Ericsson in his Monitor, launched in 1862 for service in the Civil War. Because this vessel had to navigate shallow streams, its draft was limited to eleven feet. As it was thus impossible to carry the burden of armor necessary to protect a high-sided vessel, he was obliged to design a sunken hull. Guns and gunner were protected within a covered cylindrical turret which as it turned on its vertical axis, delivered an all-round fire while the Monitor stood still. Ericsson’s original turret, and its later modifications in the leading navies of the world, are described in the Life of John Ericsson, by William Conant Church, New York, Scribner, 1890.

Lathes have given rise to planers, now built of great strength and in highly complicated designs. In a lathe the object turns upon centers against a tool; a planer carries its tool in a revolving cylinder, the work being fed in a straight line. A shaper, with much the same essential construction, moves along its work, the wood or metal operated on remaining stationary. With a planer or a shaper the size and uniformity of the work depend upon the skill of the operator. The planer has led to the invention of a machine which dispenses with this skill. Bramah, in 1811, employed a revolving cutter to plane iron, adapting to metal the familiar mechanism for planing wood. This was the beginning of the milling machine, now so remarkably developed and improved. A skilled mechanic sets the machine and the chucks which hold the work; an unskilled hand can continue the operations, his products being uniformly of the dimensions and forms desired. Intricate shapes are easily executed, quite impracticable on any other machine. At first the revolving mechanism and its cutters were a single piece of metal; to-day cutters of costly quality are inserted in cheap metal; these inserted cutters when worn out are easily replaced.

In many cases the milling machine ousts the planer as much more economical. At the shops of the Taylor Signal Company, Buffalo, a miller of the Cincinnati Milling Machine Company does nine-fold as much work as a planer. It takes a first cut 1/8 inch deep across a full width of 12 inches, makes 60 revolutions per minute, feeds .075 inch per turn, giving a table travel of 4-1/2 inches per minute, with an accuracy limit of .001 inch.

Now for a glimpse of what a great inventor had to suffer because he lived prior to the era of machine tools, before the days, indeed, of that indispensable organ of the lathe, its slide rest. The first steam engines of James Watt built at the Soho Works, near Birmingham, are thus described:--“A cast iron cylinder, over 18 inches in diameter, an inch thick and weighing half a ton, not perfect, but without any gross error was procured, and the piston, to diminish friction and the consequent wear of metal, was girt with a brass hoop two inches broad. When first tried the engine goes marvelously bad; it made eight strokes per minute; but upon Joseph’s endeavoring to mend it, it stood still; and that, too, though the piston was helped with all the appliances of hat, papier maché, grease, blacklead powder, a bottle of oil to drain through the hat and lubricate the sides, and an iron weight above all to prevent the piston leaving the paper behind in its stroke--after some imperfections of the valves were remedied, the engine makes 500 strokes with about two hundred weight of coals.” In another month or two, with better condensation, it “makes 2,000 strokes with one hundred weight of coals.”

Emery and Carborundum Wheels.

Emery, carborundum and alundum wheels are developed from the grindstone of the distant past. That stone gives a straight-line finish or edge to the surfaces submitted to it; and as the work is shifted in front of the stone these surfaces may take a curved or other contour. But a grindstone, let it be as hard as can be found, is not hard enough to take and keep any other than a cylindrical form. Its successors of to-day, the carborundum wheel especially, can be of varied shapes, and transfer these to metal with celerity and economy.

Carborundum, a compound of silicon and carbon, is produced at Niagara Falls, New York, by a process devised by Mr. E. G. Acheson. In an electrical furnace are placed granulated coke, sand, a little salt, and some sawdust to keep the mixture porous and allow generated gases to escape freely. The crystals of carborundum thus produced require seven horse-power hours for each pound; in hardness they are excelled by the diamond only. United under severe hydraulic pressure by a vitrified bond they are eight times as efficient as emery in abrasion. Carborundum wheels are replacing lathes as a means of finishing axles, piston-rods and rolls; their accuracy is unsurpassed, while they demand but one third the time needed by a steel tool.

Form in Plastic Arts.

At the very dawn of art moist clay was molded into useful plates and bowls. This foreran not only all that the potter has since accomplished, but all that has been achieved in the foundry and the mint. In making bricks, tiles, and terra cotta, the first task is to make the clay plastic, then advantage is taken of its plasticity. In like manner we heat a metal to fluidity, and then pour it into a mold to make a fence rail, a stove plate, or a car wheel. An electric bath refines upon this process. Copper, let us say, dissolves in a tank, and concurrently its particles are deposited on a mold from which the metal can be readily stripped, avoiding the distortion inevitable when heat has come into play.

Within the past ten years concrete has grown into much importance as a building material, especially as reinforced with steel. It is a great deal easier and cheaper to pour a wall into molds than to lay courses of brick, or cut and dispose stone-work. Elsewhere in this book a few pages are given to reinforced concrete, and its applications.

Pressing and Stamping.

Pressing, like molding, has of late years much extended its range of forms. In germ it goes back to the distant day when seals were impressed upon clay tablets, and coins or medals were struck from hard matrices. In glass manufacture the press has been used for centuries. Cheap pressed tumblers and bowls have long been accompanied by cheap metal pots and pans, plates and basins, stamped by machinery. To-day much enlarged and improved, such machinery, as a Bliss press, makes a kitchen sink from a sheet of steel, forms gears and pinions from round bars of metal, and executes the intricate curves of a mandolin in a plate of aluminum. For a good while the spinning lathe gave us from thin metallic sheets a variety of cups, saucers, dishes, parts of kettles, lamps, and the like. To-day each of these articles is produced by a single blow of a die, proving that metals are plastic in a degree unsuspected in former days. Thus it comes about that the seams necessary to the tinman and the coppersmith, with all their liability to leaks and uncleanliness, have been largely dismissed and may soon be wholly banished. Pressing is illustrated on pages 184 to 186 of this book.

Old and New Means of Conferring Form.

To-day we are rich in old and new facilities for the bestowal of form. To confer shape by division we have an immense variety of knives, scissors, saws, axes, hatchets and shears. These, together with hammers, chisels and gouges enable us to disengage from a mass not merely a simple rail, panel, or table-top, but a carving or a statue. Surfaces are smoothed with a rasp, a file, a plane; sand is rubbed on abrasively, or falls from a height, or is forcibly blown with a blast of steam or air. Emery either spread on paper, or glued upon a wheel, grinds with an accuracy and speed new to art; and all that emery can do is outdone by carborundum and alundum, which slice away metal as if chalk, be its hardness what it may. Perforation is accomplished with rotary drills, or by a sandblast, or on occasion by corrosive acids--a final resource in treating refractory stone. Rolls of tremendous power reduce iron and steel in thickness, and, when suitably shaped, confer form on railroad rails, girders and the like. Every tool and implement, old or new, is now embodied in machines of gigantic force, or multiple effect, so that the skill of an earlier generation is either not in demand at all or passes to tasks of a delicacy never attempted before. It is by virtue of presses, enormous in power, that to-day shapes are bestowed on metals in successful rivalry with the ancient art of the founder himself. Indeed the art of conferring form by pouring a liquid into molds is at this hour largely exercised in work where heat plays no part whatever,--as in the tasks of the builder in concrete, the labors of the electrician as he employs a bath to separate a metal from its ore, or to plate a surface with silver or gold.

Use Creates Beauty.

In strong contrast with the varied resources of modern toil are the simple tools and implements of prehistoric skill which, modified much or little, are at this hour still indispensable to the mechanic, the builder, the engineer. These simple aids early became admirable in form so as to be all the more useful. Says Mr. George Bourne:--

“The beauty of tools is not accidental but inherent and essential. The contours of a ship’s sail bellying in the wind are not more inevitable, nor more graceful, than the curves of an adze-head or of a plowshare. Cast in iron or steel, the gracefulness of a plowshare is less destructible than the metal, yet pliant, within the limits of its type. It changes for different soils; it is widened out or narrowed; it is deep-grooved or shallow; not because of caprice at the foundry or to satisfy an artistic fad, but to meet the technical demands of the expert plowman. The most familiar example of beauty indicating subtle technique is supplied by the admired shape of boats, which is so variable, says an old coastguardsman, that the boat best adapted for one stretch of shore may be dangerous if not entirely useless at another stretch ten miles away. And as technique determines the design of a boat, or of a wagon, or of a plowshare, so it controls absolutely the fashioning of tools, and is responsible for any beauty or form they possess. Of all tools, none, of course, is more exquisite than a fiddle-bow. But the fiddle-bow never could have been perfected, because there would have been no call for its tapering delicacy, its calculated balance of lightness and strength, had not the violinist’s technique reached such marvelous fineness of power. For it is the accomplished artist who is fastidious as to his tools; the bungling beginner can bungle with anything. The fiddle-bow, however, affords only one example of a rule which is equally well exemplified by many humbler tools. Quarryman’s pick, coachman’s whip, cricket-bat, fishing-rod, trowel, all have their intimate relation to the skill of those who use them; and like animals and plants adapting themselves each to its own place in the universal order, they attain to beauty by force of being fit. That law of adaptation which shapes the wings of a swallow and prescribes the poise and elegance of the branches of trees, is the same that demands symmetry in the corn-rick and convexity in the barrel; and that, exerting itself with matchless precision through the trained senses of haymakers and woodmen, gives the final curve to the handles of their scythes and the shafts of their axes. Hence the beauty of a tool is an unfailing sign that in the proper handling of it technique is present.”[8]

[8] Cornhill Magazine, London, September, 1903.

In the course of a judicious review of the mechanical engineering of machine tools, Mr. Charles Griffin has this to say regarding convenience:--[9]

[9] Engineering Magazine, New York, May, 1901.

Convenience in the Use of Machines.

“A tool is an investment, the interest which it earns depending on the amount of work it turns out in a given time. This depends largely on its convenience of manipulation, involving a study of levers, handles, wheels, knobs and other auxiliary devices, their shape and place with reference to the best adaptation to the average human frame, the ease and extent of their motions, and the rapidity with which these motions may be accomplished. The position of the operator, his natural tendencies, the motions he will go through, all have to be imagined in view of the attainment of his maximum convenience. This study, in the absence of any counterpart of the proposed machine, often forces a resort to rough models, or in lieu of this, a full-size blackboard sketch, extending to the floor, upon which the location of parts may be tried for convenience.”

Resources Rich or Meagre as Affecting Invention.

In the National Museum, at Washington, the visitor as he inspects examples of American aboriginal art is astonished at its union of utility and beauty. Boat and paddle, spear and hook, basket and vase, are as admirable in form as useful in traveling, fishing, or carrying corn or water. How far an aboriginal designer may go largely turns upon what variety of resources Nature offers him. No few score families on a lonely islet of the Pacific can possibly rival the cloths and carvings displayed by tribes ranging a Pennsylvania, or a California, abounding with diverse minerals, plants and animals. When skill and invention occupy so rich a land they flower into the highest creations of aboriginal art. And yet it may be that the very fewness of a designer’s resources but spurs him to all the more ingenuity. It depends upon who the man is. As we look upon a collection of Eskimo harpoons and knives, coats and kayaks, we marvel that all these should be produced with so much excellence and variety from a scanty store of bones and teeth, sinews and hides, with but little iron or none at all.[10]

[10] Two unrivalled books on aboriginal invention have been written by Mr. Otis T. Mason, Curator of the Department of Ethnology at the National Museum, Washington:--“Woman’s Share in Primitive Culture,” New York, D. Appleton & Co., 1894; and “The Origin of Inventions,” London, Walter Scott Publishing Co., and New York, C. Scribner’s Sons, 1905. Both volumes are fully illustrated.

The annual reports of the Bureau of Ethnology, Smithsonian Institution, Washington, describe and illustrate American aboriginal art so fully and admirably as to be indispensable to the student.